A conventional bevel needle used for medicinal injections or blood-drawings has cutting edges in the front-end portion of the bevel needle, where the cutting edges are of an acute pointed-arch shape with a semi-circular profile along the external circumferential surface of the bevel needle when seen from front. When the needle axis is held horizontal with the open bevel end surface facing upward, these cutting edges are formed by right and left ground surfaces that cross the external circumferential surface of the bevel needle or by right and left ground surfaces that cross the open bevel end surface of the bevel needle. The right and left ground surfaces cross each other at the front end of the bevel needle and extend diagonally rearwardly and symmetrically with respect to a vertical plane containing the needle axis. Both the right and left side ends of the cutting edges have acute apex angles.
Because of having acute cutting edges, such a conventional bevel needle enables easy puncturing but causes a semi-circular wound in bio-tissue, such as a dura mater and a blood vessel punctured. The semi-circular wound not only tends to curl up, thereby causing lengthened time for curing, but also, when a blood vessel is punctured, the semi-circular wound in the blood vessel wall would curl up causing medicinal solution injected into the blood vessel to leak into the patient's body, and, when a subarachnoid space is punctured, the semi-circular wound in the covering dura mater would curl up causing spinal fluid to leak into the patient's body, thereby inflicting a long-time pain on the patient.
The present invention is made to solve the problem described above. Thus, an object of the present invention is to provide a medical bevel needle that enables easy puncturing but does not cause a semi-circular wound in the bio-tissue punctured that tends to curl up.